quoted phrase search has false positives

[Ian Jackson]

I visited
 https://bugs.launchpad.net/ubuntu/+bugs?advanced=1
and selected:
 Search term: "memory card"
 (ie, I typed both quotes into the form)
 by importance
 All Status ticked except Rejected
 No importance ticketed
 Assignee: doesn't matter
 Reporter: <blank>
 Not release-specific
 Upstream status: doesn't matter
 Do not hide duplicate bugs
 Do not only show bugs with patches
 Hide bugs with packages specified
 No tags

And one of the bugs which this found was
 https://bugs.launchpad.net/ubuntu/+source/linux-source-2.6.15/+bug/8389
which contains the word `card' and the word `memory' but not the phrase `memory card'.

This makes it unnecessarily difficult to search for some things.